Segfault in `test_sampling_profiler`

Crash report

What happened?

A recent Buildbot run (AMD64 Debian root) saw a segfault in test_sampling_profiler: https://buildbot.python.org/#/builders/345/builds/12988

test_sampling_all_threads (test.test_profiling.test_sampling_profiler.test_integration.TestSampleProfilerIntegration.test_sampling_all_threads) ... Fatal Python error: Segmentation fault

Current thread 0x00007f85531fa740 [python] (most recent call first):
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/profiling/sampling/sample.py", line 75 in sample
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/profiling/sampling/sample.py", line 350 in sample
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/test_profiling/test_sampling_profiler/test_integration.py", line 521 in test_sampling_all_threads
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/case.py", line 613 in _callTestMethod
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/case.py", line 667 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/case.py", line 723 in __call__
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 122 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 84 in __call__
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 122 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 84 in __call__
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 122 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 84 in __call__
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 122 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 84 in __call__
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 122 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 84 in __call__
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/runner.py", line 257 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/single.py", line 84 in _run_suite
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/single.py", line 42 in run_unittest
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/single.py", line 162 in test_func
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/single.py", line 118 in regrtest_runner
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/single.py", line 165 in _load_run_test
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/single.py", line 210 in _runtest_env_changed_exc
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/single.py", line 319 in _runtest
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/single.py", line 348 in run_single_test
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/worker.py", line 99 in worker_process
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/worker.py", line 134 in main
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/worker.py", line 138 in <module>
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/runpy.py", line 87 in _run_code
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/runpy.py", line 196 in _run_module_as_main

Current thread's C stack trace (most recent call first):
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _Py_DumpStack+0x33 [0x563947ed22d4]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x3285b2 [0x563947eea5b2]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x328caa [0x563947eeacaa]
  Binary file "/lib/x86_64-linux-gnu/libc.so.6", at +0x3bfd0 [0x7f8553238fd0]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _PyEval_EvalFrameDefault+0x5795 [0x563947e2bc9a]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x280c92 [0x563947e42c92]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x280e44 [0x563947e42e44]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _PyFunction_Vectorcall+0x54 [0x563947cee2da]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12f1c1 [0x563947cf11c1]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12f326 [0x563947cf1326]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12da86 [0x563947cefa86]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12dd76 [0x563947cefd76]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at PyObject_Call+0x20 [0x563947cefdae]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _PyEval_EvalFrameDefault+0x60a2 [0x563947e2c5a7]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x280c92 [0x563947e42c92]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x280e44 [0x563947e42e44]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _PyFunction_Vectorcall+0x54 [0x563947cee2da]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12d7d3 [0x563947cef7d3]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12d99d [0x563947cef99d]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x1c26af [0x563947d846af]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x1c278d [0x563947d8478d]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _PyObject_MakeTpCall+0xce [0x563947cee47c]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12c6af [0x563947cee6af]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at PyObject_Vectorcall+0x23 [0x563947cee6fd]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _Py_VectorCall_StackRefSteal+0x86 [0x563947e237d2]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _PyEval_EvalFrameDefault+0x90b2 [0x563947e2f5b7]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x280c92 [0x563947e42c92]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x280e44 [0x563947e42e44]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _PyFunction_Vectorcall+0x54 [0x563947cee2da]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12f1c1 [0x563947cf11c1]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12f326 [0x563947cf1326]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12da86 [0x563947cefa86]
  <truncated rest of calls>

A similar crash happened earlier in the run in test_sampling_with_collapsed_export.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

No response

まず、報告された75行目と350行目付近の Lib/profiling/sampling/sample.py から始め、次に test_sampling_all_threads と test_sampling_with_collapsed_export 付近の Lib/test/test_profiling/test_sampling_profiler/test_integration.py を調べます。Linux 上で失敗する sampling-profiler テストを再現し、segfault を追跡します。影響を受けるテストが segmentation fault なしで完了し、回帰が関連するテストスイートでカバーされれば完了です。